This invention relates, in general, to surface imaging probes, and more particularly, to probes that provide atomic force microscopy images and methods for forming such probes.
To investigate the failure modes of semiconductor devices, it is very advantageous to be able to generate images of the surface of the semiconductor device. Such images have been traditionally formed using atomic force microscopy (AFM). A probe tip is dragged across the surface of the semiconductor device and the topography of the surface is measured by an optical signal which is reflected off of a mirror affixed to the probe. Movement of the probe will result is a corresponding motion in the mirror. To mount the mirror, an insulating epoxy or an insulating layer is used to electrically isolate the mirror from the AFM probe. Due to the thermal conditions of operation, this insulation can breakdown with time and cause the probe to fail. An additional problem with the mirror is that they are typically mounted to the probe at a significant distance away from the probe tip. As a result, the motion of the mirror does not necessarily replicate the motion of the probe, and there is a loss of accuracy in the measuring of the topography of the surface.
In addition to the AFM, a thermal image of the device's surface is very valuable in identifying hot spots. To produce a thermal image, a previously known method forms the AFM probe from a thermocouple which measures the temperature of the surface as the probe is moved. However a disadvantage is that the thermal energy of the semiconductor device is transferred to the reflective mirror which can create noise in both the topographical image and the thermal profile of the semiconductor device.
By now, it should be appreciated that it would be advantageous to provide an improved method for forming an AFM/thermal image probe that does not require the use of a mirror mounted to the probe. It would of further advantage if the probe were easier to manufacture and more reliable than previously known imaging probes.